U.S. patent number 5,425,279 [Application Number 08/125,960] was granted by the patent office on 1995-06-20 for vessel inspection system.
This patent grant is currently assigned to Atlantic Richfield Company. Invention is credited to Richard D. Clark, Thomas M. Robins, Daryl K. Rutt, John D. Stratton, Daniel L. Torres.
United States Patent |
5,425,279 |
Clark , et al. |
June 20, 1995 |
Vessel inspection system
Abstract
Petroleum coking drums and other vessels may be inspected to
determine if dimensional changes or bulges have occurred in the
surface of the vessel by an inspection device including a reflected
laser light measuring survey apparatus and a video camera mounted
on a frame which may be disposed in selected vertical positions
along a central axis of the vessel and rotatably positioned by a
rotary positioner interposed between a support stem for the device
and the frame. Plural distance measurements and video scans are
transmitted to a remote control console for recording and plotting
of the contours of bulges or other dimensional anomalies surveyed
by the survey apparatus. Components of the device are sealed or gas
pressurized to minimize the chance of explosion in hazardous
environments such as the interior of a petroleum coking drum. The
system is adapted to be supported on the distal end of a coking
drum drillstem and centralized by a removable clamp unit mounted on
the drum manway flange. Data regarding the positions of the
measured points may be converted for display using a CAD computer
program to illustrate bulge contours and peaks indicative of
unusual stress or degradation of the vessel structure.
Inventors: |
Clark; Richard D. (Ontario,
CA), Rutt; Daryl K. (Ontario, CA),
Stratton; John D. (Ontario, CA), Robins; Thomas
M. (Bellingham, WA), Torres; Daniel L. (Bellingham,
WA) |
Assignee: |
Atlantic Richfield Company
(Plano, TX)
|
Family
ID: |
22422261 |
Appl.
No.: |
08/125,960 |
Filed: |
September 23, 1993 |
Current U.S.
Class: |
73/865.8 |
Current CPC
Class: |
C10B
45/00 (20130101); G01B 11/24 (20130101) |
Current International
Class: |
G01B
11/24 (20060101); G01M 019/00 () |
Field of
Search: |
;73/623,865.8
;356/376,378,384,428 ;348/82-85 ;376/248,249 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Raevis; Robert
Attorney, Agent or Firm: Martin; Michael E.
Claims
What is claimed is:
1. A vessel inspection system for surveying the interior surface of
a vessel to determine dimensional changes in said vessel, said
system including a device comprising:
a frame;
a survey apparatus mounted on said frame and operable to measure
the distance between a reference point and said interior surface of
said vessel and to transmit signals relating to said distance
measurement;
a support for supporting said frame for movement within said vessel
along an axis;
a positioner for positioning said frame and said apparatus
rotationally with respect to said axis at a selected number of
positions for measuring the distance from said reference point to
said surface;
means for recording signals relating to the distances measured by
said survey apparatus, the rotary position of said survey apparatus
with respect to said vessel and the position of said survey
apparatus along said axis within said vessel; said survey apparatus
including a signal source operable to scan a predetermined area of
said surface of said vessel and a triangulation camera operable to
focus on said signal for determining the distance between said
reference point and said surface of said vessel;
an enclosure for said survey apparatus and a source of pressure gas
connected to said enclosure for pressurizing said enclosure to
minimize incursion of combustible vapor into said enclosure, said
survey apparatus including two spaced apart lenses, each of said
lenses including a gas curtain shroud associated therewith and
operably connected to said source of pressure gas for maintaining
said lenses substantially free of foreign matter during operation
of said apparatus;
a video camera supported on said frame and operably connected to at
least one of a monitor and recording means for providing video
scanning of said surface of said vessel;
a camera positioner supported on said frame and operable to
position said video camera for viewing substantially all of the
interior surface of said vessel by said video camera, said camera
positioner being operable to position said video camera about two
mutually perpendicular axes and wherein one of said axes coincides
with said axis of said vessel during operation of said system;
floodlight means supported on said frame for illuminating said
surface of said vessel for viewing by said video camera;
a clamp unit adapted to be supported on said vessel for clamping
said support in a predetermined lateral and vertical position with
respect to said axis of said vessel during operation of said
system; and
an accelerometer means supported on said frame and operable to
sense vibrations of said apparatus, said accelerometer means being
operably connected to signal generating means for generating an
alarm signal indicative of excessive vibration of said device
during operation of said survey apparatus.
2. A system for inspecting the interior of a vessel comprising:
a device insertable in said vessel including a frame, a survey
apparatus mounted on said frame and operable to measure the
distance between a reference point and the interior surface of said
vessel and to transmit signals relating to plural distance
measurements to means for recording said signals, a video camera
supported on said frame and operably connected to at least one of a
monitor and recording means for providing video scanning of said
surface, a positioner connected to said frame and to said video
camera for positioning said video camera with respect to said frame
to scan the interior surface of said vessel and floodlight means
supported on said frame for illuminating said surface of said
vessel for viewing by said video camera;
a positioner operable to interconnect said frame with a support for
positioning said frame rotationally with respect to an axis of said
vessel in a selected number of positions for measuring the distance
from said reference point to said surface;
control means for moving said device along said axis of said vessel
and for rotationally positioning said device in said vessel to scan
a predetermined portion of said surface for making distance
measurements between said surface and said reference point and for
video scanning a predetermined area of said surface; and,
an accelerometer means supported on said frame and operable to
sense vibrations of said apparatus, said accelerometer means being
operably connected to signal generating means for generating an
alarm signal indicative of excessive vibration of said device
during operation of said survey apparatus.
3. The system set forth in claim 2 wherein:
said camera positioner is operable to position said video camera
about two mutually perpendicular axes, one of said axes coinciding
with said axis of said vessel during operation of said device.
4. The system set forth in claim 2 including:
a clamp unit adapted to be supported on said vessel for clamping
said support in a predetermined lateral and vertical position with
respect to said axis of said vessel during operation of said
device.
5. A method for inspecting the interior surface of a generally
cylindrical petroleum coking drum comprising the steps of:
providing an inspection device including a survey apparatus for
measuring the distance between a reference point with respect to a
central longitudinal axis of said drum and the interior surface of
a wall of said drum for locating one of bulges or distortions of
said wall;
connecting said device to a support for moving said device along
said axis within said drum;
positioning said device along said axis with said support;
determining the distance from said device to a predetermined point
on said drum;
measuring the distances of a plurality of points between said
surface and said reference point at a predetermined position of
said survey apparatus in said drum;
rotating said device to another position about said axis and making
measurements of the distances between said surface and said
reference point of another plurality of points on said surface;
moving said survey apparatus along said axis and making
measurements of the distances between said surface and said
reference point of a still further plurality of points on said
surface; and,
sensing vibrations of said device and generating an alarm
indicative of excessive vibration during operation of said
device.
6. The method set forth in claim 5 including the step of:
plotting the measurements of said distances of substantially all of
said plurality of points on said surface to provide a planar
development of the interior surface of said drum.
7. The method set forth in claim 6 including the step of:
overlaying the plot of said plurality of points with a
representation of a known anomaly of said surface of said drum.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to an inspection system for the
internal surfaces of enclosed vessels, particularly coke drums and
the like, wherein a combination of a distance measuring survey
instrument and video camera are cooperatively operated to inspect
the internal surfaces of the vessel for deterioration and
distortion.
2. Background
Many enclosed vessels require, or desirably should undergo,
periodic inspection to detect structural anomalies or other
conditions which may eventually lead to vessel structural
deterioration or failure. For example, it is desirable to
frequently inspect the interior surfaces of vessels known as coke
drums used in petroleum coking operations to determine if bulging
or distortion of the drum surfaces has occurred and/or if other and
visual signs of deterioration are present. Vessels such as
petroleum coking drums may be on the order of twenty feet to thirty
feet in diameter and fifty feet to seventy feet in height. These
vessels are subjected to thermal and mechanical stresses which,
without periodic monitoring, can lead to early and unexpected
structural failure. One problem encountered in inspecting petroleum
coke drums and similar vessels pertains to the fact that the
exterior surfaces of these vessels are clad with an insulating
blanket or other protective structure which prohibits easy visual
inspection of bulges or similar distortions in the drum structure.
Such bulges are usually indicators of structural deterioration of
the drum.
Heretofore, for example, petroleum coke drums have been inspected
by emptying coke from the drum, thoroughly washing and purging of
the drum interior space and erecting a scaffolding in the interior
of the drum so that inspection personnel may make essentially
manual dimensional measurements to detect changes in shape of the
drum structure, such as bulges in the cylindrical surface, which
would indicate a weakness in the drum and possible early failure.
Clearly, the time, expense and hazards associated with this type of
inspection procedure are such as to bring forth the realization of
a need to improve the inspection process. Similar types of vessels
which are required or are desirably inspected from the interior
should also benefit from a solution to the abovementioned
problem.
SUMMARY OF THE INVENTION
The present invention provides a unique inspection system and
method for visually and dimensionally inspecting the interior
surfaces of a vessel, including a closable vessel such as a
petroleum coking drum.
In accordance with an important aspect of the present invention, a
vessel inspection system is provided which includes a device
insertable into the interior of a vessel in a stand-off position
from the vessel wall surfaces and wherein the inspection system
includes a remotely disposed distance measuring or range measuring
apparatus and a visual inspection apparatus, such as a video
camera. The vessel inspection device includes a support frame which
may be rotated to provide for scanning the entire interior
circumference of a vessel. Certain surfaces which are not normal to
a central axis of the vessel may also be visually inspected by the
video camera which may be panned and tilted to cover the entire
interior surface of the vessel.
The inspection system of the present invention is adapted to
minimize the chance of igniting hazardous vapors which may be
present in the interior of a vessel and the system may be operated
remotely, thereby eliminating the requirement to place operating
personnel within the vessel. In a preferred embodiment, the
inspection device is adapted to be disposed on a drillstem, which
may be moved generally vertically within the vessel by a
conventional hoisting apparatus, and which is normally used to
inject high-pressure water into the interior of the vessel for
cutting and drilling material disposed in the vessel. A detailed
description is provided herein of an embodiment of the invention
adapted for generally vertical movement within a petroleum coking
drum. However, those skilled in the art will recognize that the
system and method may be used to inspect vessel interiors extending
horizontally or at other angles. Moreover, the term vessel as used
herein may include structures such as pipe as well as other
containers which are not necessarily of a geometry the same as
described in detail below.
In accordance with another important aspect, the present invention
provides an improved method for inspecting the interior of a
substantially closed vessel by remote control wherein a video scan
of the interior of the vessel and a bulge measurement scan of the
interior of the vessel may be carried out and recorded,
respectively, and coordinated to provide an improved inspection
process. In particular, the bulge measurement or dimensional
measurement process is adapted to produce a video display or
printed record of bulges or distortion in the vessel surfaces with
respect to dimensional reference points such as weld seams and
other suitable reference points. In accordance with the present
invention, the results of each inspection may be compared with
previous inspections to determine changes in bulge or surface
distortion patterns which might be indicative of the useful life of
the vessel.
Those skilled in the art will recognize the above-described
advantages and features of the invention together with other
superior aspects thereof upon reading the detailed description
which follows in conjunction with the drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an elevation of the vessel inspection system shown in
place for inspecting the interior of a vessel such as a petroleum
coking drum;
FIG. 2 is a plan view showing the stem clamp unit mounted on the
drum top flange;
FIG. 3 is a front elevation of the inspection device of the
system;
FIG. 4 is a side elevation of the inspection device; and
FIG. 5 is a schematic diagram of the major elements of the
system.
DESCRIPTION OF PREFERRED EMBODIMENTS
In the description which follows, like parts are marked throughout
the specification and drawing with the same reference numerals,
respectively. The drawing figures are not necessarily to scale in
the interest of clarity and conciseness.
Referring to FIG. 1, there is illustrated a major part of a vessel
inspection system in accordance with the present invention and
generally designated by the numeral 10. The inspection system 10
includes a unique inspection device 11 shown disposed within the
interior of a closable vessel 12 characterized as a petroleum
coking drum. The coking drum 12 is a generally cylindrical vessel
having a cylindrical sidewall 14, a head 16 and a frustoconical
lower distal end portion 18 terminating in a bottom discharge
opening 20 which may be closed by a suitable cover, not shown. The
head 16 includes a cylindrical hatch delimited by a coaming 22, a
flange 24 and a hinged cover 26 shown in the open position. The
vessel 12 is typically covered with an insulating blanket 13 over
substantially its entire exterior surface.
FIG. 1 illustrates the inspection device 11 connected to an
elongated stem 30 comprising a cylindrical pipe which extends into
the interior of the vessel 12 through the manway or hatch coaming
22. The stem 30 is preferably suspended from a suitable motor
operated hoist 32 disposed above the vessel 12 and operable to move
the stem 30 from a raised position out of the interior 15 of the
vessel to the position shown in FIG. 1 and to a further lowered
position to allow the device 11 to inspect the entire interior
surface of the vessel. In order to facilitate the use of the system
10 to make high-resolution video recordings of the interior surface
of the vessel 12 and to make precise measurements of distortion or
dimensional changes in the general shape of the vessel, it is
important to stabilize and clamp the stem 30 during operation of
the inspection device 11. In this regard, a unique stem clamp unit
36 is shown disposed on the flange 24, suitably secured thereto,
and adapted to centralize and clamp the stem 30 during operation of
the inspection system 10.
Referring to FIG. 2 also, the stem clamp unit 36 includes a
generally rectangular frame 38 having vertically spaced apart
members 40 and 42, each of which support opposed clamping jaws 44,
as shown by way of example in FIG. 2. The frame members 40 and 42
are open to one side as shown in FIG. 2 to permit lateral insertion
of the stem 30 within the frame 38. The stem clamping jaws 44 are
operable to be biased in their stem clamping positions by suitable
actuators 46 which may comprise power operated actuators or
so-called toggle type actuators such as a type manufactured by
Automation Products Group of Mt. Clemens, Mich. The actuators 46
are operable to cause the jaws 44 to releasably grip the stem 30 to
centralize it along the central longitudinal axis 48 of the vessel
12 and to prevent lateral or vertical movement of the stem during
operation of the inspection device 11. The stem 30 normally
functions to carry a suitable coke drilling apparatus at its lower
distal end 31 such as a high-pressure water jet type drill for
cutting petroleum coke out of the interior 15 of the vessel 12 for
discharge through the bottom opening 20. Accordingly, the
inspection device 11 may be conveniently mounted on the distal end
31 of the stem 30 in place of the drilling means, not shown. In
this regard, a suitable coupling section 50 is provided for the
inspection device 11 for releasably coupling the device to the
lower end of the stem 30 when an inspection procedure is to be
carried out.
Petroleum coking drums, in particular, undergo severe thermally
induced stress cycles during the process of producing petroleum
coke and removing the coke from the interior of the drum. One
method of monitoring the structural integrity of a coke drum is to
inspect the interior surface for distortion or "bulging" of the
cylindrical wall 14. Dimensional distortion or bulging is an
indication of degradation of the vessel and dimensional
verification or monitoring of the bulging may be used to predict
when major repair or replacement of a coking drum is required. The
process of inspecting a vessel such as a petroleum coking drum is
complicated by the exterior insulation jacket or blanket 13 which
precludes convenient inspection of the drum for detection of the
inception or growth of bulging from the vessel exterior. Moreover,
it is also advisable to make visual inspections of the interior
surface of a vessel such as a petroleum coking drum to detect other
anomalies such as the loss of surface cladding or deterioration of
seam welds, etc.
Referring now to FIGS. 3 and 4, the inspection device 11 is further
characterized by an elongated frame 56, including an upper
transverse flange part 58, which is suitably connected to a motor
operated rotary positioning mechanism 60. The rotary positioner 60
is also adapted to be connected to the coupling part 50 and is
operable, upon command by remote control, to rotate the inspection
device 11, including the frame 56, with respect to the coupling 50
about a central axis 62 which, in operation of the device 11,
coincides with the axis 48. The rotary positioner 60 may be of a
type commercially available such as a Model 10R180, manufactured by
DCI of Franklin, Mass. The frame 56 also supports an inspection or
survey apparatus, generally designated by the numeral 66, for
measuring the distance between the axis 62 and the interior surface
of the vessel section 14.
The apparatus 66 is of a type commercially available which utilizes
a directable focused light or "laser" beam which is projected from
a lens 68 against the interior surface of the wall section 14,
which light beam is reflected back through a lens 70 and is viewed
by a so-called triangulation camera disposed within an enclosure 67
of the apparatus 66. The apparatus 66 has internal circuitry
adapted to measure the distance between a reference point on the
apparatus and the surface from which the laser light beam is
reflected back to the camera lens 70. The directable laser light
beam may be adapted to cover a target surface area of about five
feet by seven feet at a stand-off of about thirteen feet from the
surface of the section 14, for example. The minimum spacing of
distance measurements at the above-mentioned stand-off distance
coordinates on a one inch by one inch grid, and distance
measurement resolution is less than 0.125 inches at these
conditions. Accordingly, the apparatus 66 is operable to measure
slight bulges or deformities in the cylindrical section 14 of the
vessel 12. The apparatus 66 may be of a type commercially available
such as a Model 62LS Range Camera manufactured by Range Vision,
Inc. of Burnaby, British Columbia. The apparatus 66 is equipped
with the abovementioned suitable laser light source, triangulation
camera and horizontal and vertical scanning drives for the laser
light source. The apparatus 66 is also equipped with a suitable
sensor to detect sensing head vibration which might interfere with
the accuracy of the distance measuring capability of the apparatus.
The enclosure 67 is modified to be gas pressurized to minimize the
chance of explosion when the apparatus 66 is disposed in a
potentially hazardous environment such as the interior 15 of the
coking drum 12. The lenses 68 and 70 are also modified to provide
for suitable gas curtains to flow thereover to prevent fouling of
the lens surfaces. In this regard, the lenses 68 and 70 are
provided with suitable ported shrouds 69 and 71 which are operable
to receive a lens washing or curtain fluid such as an inert gas, or
so-called instrument air, conducted to the device 11 from a conduit
74, FIG. 3. The lens washing or gas curtain devices, including the
shrouds 69 and 71, may be of a type commercially available, such as
a model PELCO E700A from Gullevin International of St. Laurent,
Quebec.
The frame 56 includes a lower transverse flange 80 on which is
mounted a motor operated positioning mechanism, generally
designated by the numeral 82, for supporting and positioning a
camera 84 having a viewing lens 86 also protected by an air curtain
shroud 88, FIG. 3. The camera 84 is suitably mounted on the
positioning mechanism 82 for positioning the camera lens 86 about
the axis 62 and also about an axis 63 normal to the axis 62.
Accordingly, the camera 84 may be panned about the axis 62 and
tilted about the axis 63 to view the entire interior surface of the
vessel 12, for example. The camera 84 is enclosed in an
explosion-proof housing 85 and the air curtain shroud 88 is also in
communication with the conduit 74 to receive lens washing gas
therefrom. The camera 84 may be of a type operable to have a
minimum resolution of 300 equivalent standard television lines and
may be of a type commercially available such as a Model SSC-C370
12vDc manufactured by Sony Corporation of Park Ridge, N.J. The lens
86 may also be of a type commercially available such as a Model
C-31002, manufactured by Cosmicar and having a "zoom" or
magnification ratio of about 12 to 1 with remote control of zoom
and focus. The positioner 82 is also of a type commercially
available such as a Model PT1250 EX/PP, manufactured by Pelco of
Clovis, Calif., having a pan range of at least plus or minus thirty
degrees (.+-.30.degree.), a tilt range of at least seventy five
degrees (75.degree.) to minus fifteen degrees (-15.degree.) from
the horizonal with adjustable limit stops for both pan and tilt
motions, a preset center position in both the pan and tilt drive
modes with position feedback signals for both the pan and tilt
positioning operations.
As shown in FIGS. 3 and 4, the device 11 also includes spaced apart
generally horizontally projecting floodlights 90 which are operable
to illuminate the interior surface of the vessel 12 for suitable
viewing by the camera 84. The floodlights 90 may be of a type
available from Cooper Industries, Inc., Houston, Tex., under the
trademark Crouse Hinds as Model RCDE-6.
As also shown in FIGS. 3 and 4, the frame 56 may be mounted on a
suitable rest support or stand 99 when servicing or repairing the
device 11, and the frame 56 includes opposed support tubes 100 for
receiving removable support beams 102, one shown in FIG. 4, whereby
the device 11 may be temporarily supported on the flange 24, for
example, to facilitate coupling and decoupling the device with
respect to the stem 30. The support bars 102 may, of course, be
removed from the support tubes 100 when it is desired to lower the
device 11 into the interior 15 of the vessel 12. As shown in FIGS.
1 and 3, electrical control signals to and from the positioner 60,
the apparatus 66, the positioning unit 82, the camera 84 and the
floodlights 90 may be carried by suitable conductors, not shown,
through a suitable junction enclosure 110 mounted on the frame 56
and then through a suitable bundled conductor 112 which may be
disposed in a sleeve 114 together with the conduit 74. The
multiconductor cable and sleeve assembly 114 may extend from the
interior 15 of the vessel 12, for example, through the bottom
opening 20 to a suitable control console to be described in further
detail herein.
As shown in FIG. 3, instrument air or purge gas may be conducted to
a suitable control unit 116 mounted on the frame 56 and operable to
monitor the flow of purge gas to and from the enclosure 67 of the
apparatus 66. The control unit 116 may also be of a type
commercially available such as a Model 1001A, manufactured by
BEBCO. Basically, the control unit 116 monitors the pressure within
the interior of the enclosure 67 and operates a suitable alarm if
that pressure decreases below a predetermined value indicating a
possible leak of purge gas of unacceptable proportions from the
enclosure 67.
Referring now to FIG. 5, there is illustrated a block diagram of
the major components of the system 10 including those components
which are disposed on the frame 56. As illustrated in FIG. 5, the
vertical positioning hoist 32 is operable by a suitable controller
33 for positioning the stem 30 and the device 11. FIG. 5 also shows
that the control console may be divided into two separate control
panels, one for controlling the operation of the system 10 to make
dimensional measurements or so-called bulge measurements of the
section 14 of the vessel 12 and a separate control panel for
operating the video camera 84. As illustrated in FIG. 5, a control
panel 120 may be provided to include a controller 122 for operating
the rotation motor of positioner 60 and a digital computer or
central processing unit 124 for controlling the operation of the
inspection or survey apparatus 66 and for receiving data from the
apparatus 66 to provide data and a suitable visual display of the
dimensional changes in the surface of the section 14o The control
panel 120 also includes a rack mounted power supply unit 126 for
supplying power to the apparatus 66. The power supply unit 126 is
operable to supply electrical power to the processing unit 124
also.
The processing unit 124 may be of a type operable to run on MS DOS
based software, such as a so-called IBM type compatible computer.
The processing unit 124 is equipped with a suitable visual monitor
125 and keyboard 127 and is adapted to be programmed to calculate
and store coordinate data received from the apparatus 66 and
display related images on the monitor 125. The processing unit 124
is also adapted to allow operator control of the scanning area of
the laser light beam as well as data point spacing in the
horizontal and vertical or so-called x and y directions. Additional
features include the ability to combine individual scenes of the
surfaces measured into so-called ring and complete surface models.
Data from the processing unit 124 may be processed off-line to
overlay weld seam locations in accordance with vessel design, add
particular information regarding identification of the vessel and
produce suitable displays indicating a planar developed view of the
vessel surface showing bulge contour lines and peaks as well as a
three-dimensional view of the vessel with bulge areas shaded, for
example.
Referring further to FIG. 5, the control console also includes a
video monitoring control panel 130 which includes a power supply
132 for vibration sensing accelerometers 134 which are suitably
mounted on the frame 56 to indicate if a vibration level exists
during operation of the system 10 which is unacceptable for
measuring with the apparatus 66. A suitable audio and/or visual
alarm 136 is also provided on the panel 130 to indicate when a
possible leak is occurring in the enclosure 67 of the apparatus 66.
As illustrated, the panel 130 includes a suitable switch 138 for
controlling the floodlights 90, a control unit 140 for the pan and
tilt positioning unit 82 and a controller 142 for operating the
zoom lens 86.
The camera 84 is operably connected to a suitable power supply 144,
a video recorder 146 and a suitable video monitor 148, all at the
panel 130.
An operation to inspect the interior of a vessel such as the drum
12 is preceded by removal of all material from the interior 15 of
the vessel, opening the hatch cover 26 and providing access to the
bottom opening 20. Preferably, the temperature within the interior
15 is reduced to about 100.degree. F. and the stem 30 is raised to
a point so that its lower distal end 31 is above the flange 24.
Typically, the inspection device 11 is provided with the support
bars 102 and is lowered into the opening in the flange 24 so that
the support bars are resting on the flange. At this time the stem
30 is lowered and connected to the coupling 50. The control cable
assembly 114 is connected to the device 11, lowered through the
vessel 12 and out the bottom opening 20 for connection to an
extension of the control cable leading to the control console which
includes the panels 120 and 130.
At this time the stem 30 may, if not previously adapted, be
provided with a suitable linear measurement scale or tape measure,
for example, suitably connected to its exterior surface for
reference of the vertical position of the device 11 once it is
lowered into the interior 15. Alternatively, the hoist 32 may be
provided with a suitable readout device to indicate linear movement
of the stem 30. Once the control cable 114 is suitably connected to
the device 11 and to the control console, the support bars 102 may
be removed from the frame 56 and the device lowered into the
interior 15 by lowering the stem 30 with the hoist 32. The position
of the device 11 with respect to the flange 24 is noted for each
vertical change in position of the device within the interior of
the vessel 12.
When the device 11 has been lowered below the flange 24, the clamp
unit 36 is installed on the flange with the clamping jaws 44
retracted so that they may be positioned around the stem 30. When
the clamp unit 36 has been suitably secured to the vessel 12 and
the device 11 positioned in an initial position for inspecting the
interior of the vessel, the actuators 46 are operated to cause the
jaws 44 to firmly grip the stem 30 holding it in a centralized
position aligned with the axis 48.
Once the device 11 has been centralized and is ready for operation,
an inert pressure gas or so-called instrument air is supplied
through the conduit 74 to pressurize the enclosure 67 and to begin
washing the lenses 68, 70 and 86. Proper pressurization of the
enclosure 67 is verified through the control unit 116 by a lack of
an alarm signal from the alarm 136. Verification of the operability
of the positioners 60 and 82 together with the operability of the
camera 84 and the survey apparatus 66 is also carried out. A
calibration measurement may also be carried out on the apparatus 66
from a known reference point, if available.
Certain position sensors on the positioners 60 and 82 may be read
to indicate the position of the device 11 including the apparatus
66 and the camera 84. The positioner 82 is also set to a "centered"
position which will align the lens of the camera 84 with a
"centered" position of the survey apparatus 66. If the device 11 is
not vertically positioned in a location to begin a survey or
inspection of the interior of the vessel 12, the clamps 46 are
released and the hoist 32 is operated to vertically position the
device in a starting position and the clamps 46 are then actuated
to re-engage the jaws 44 firmly with the stem 30. The positioner 60
is then operated to rotate the device 11 to a starting position
which may be from any reference point on the drum or vessel 12 such
as a port, welded seam or other landmark. The starting vertical and
rotary positions of the device 11 are then recorded as a "null"
position.
At this point the floodlights 90 may be illuminated and an overall
view of the interior surface of the vessel may be initiated by
operation of the camera 84 using the positioner 82 and the lens
controller 142 to cause the lens 86 to magnify an area of interest
on the monitor 148. If a record of the magnified area is required,
then the recorder 146 is operated to begin recording the output
signal from the camera 84. Voice-over of the tape being recorded by
the recorder 146 may be carried out to provide comments on features
being recorded.
After video scanning and recording is conducted, the floodlights 90
are extinguished and the bulge measurement scan or survey is
initiated. The vertical and rotary position of the survey apparatus
66 may be recorded on the processing unit 124 and a survey is then
initiated by the apparatus 66 to scan and store the resulting
measurement points in the processing unit 124. If further scenes at
the vertical position of the system 10 are required, such as up to
a full circumferential or "ring" scan, then the positioner 60 is
operated to index the device 11 to rotate about the axes 48, 62 to
a new position and the steps of performing the video scan and at
least the bulge survey or measurement scan is repeated. Once all of
the interior surface of the vessel 12 which can be covered at a
predetermined vertical position of the device 11 is viewed,
surveyed and recorded, the device 11 may be positioned at a new
vertical position within the vessel and the above steps carried out
until all of the interior surface area of the vessel is inspected
or surveyed, as desired.
Upon completion of a survey of the vessel 12, the clamp assembly 36
is removed from the flange 24 and the stem 30 is raised to remove
the device 11 from the interior 15 whereupon the support bars 102
are reinserted in the frame 56 and the support stand 99 is suitably
attached to the bottom of the frame. The stem 30 is then returned
to normal operation and the inspection system 10 is removed from
the vicinity of the vessel 12, including the aforementioned control
console and related components.
Since the processing unit 124 has stored data indicating the
distances from the axis 48 of plural points on the interior surface
of the section 14 of the drum, which points are preferably spaced
about one inch apart on a rectangular grid, this data may be used
to generate or be merged into a model or map of the entire interior
surface of the drum section 14 which has been surveyed using
previously logged vertical and rotary scene positions of the
various areas inspected or surveyed by the apparatus 66. The
scenes, ring scans or entire surface scans may be converted to a
suitable data format which will enable the data to be used in
conjunction with a commercially available computer-aided design
computer program such as one designated by the trademark AUTOCAD.
The data converted for use with the AUTOCAD program may be
overlayed with data representing welded seams or other known
anomalies of the vessel interior. The program may then be used to
provide so-called layout views showing bulge contour lines or peaks
as well as a three-dimensional view of the interior of the vessel
12 showing the bulge areas in a shaded form. The survey may be
compared with previous surveys to determine changes in bulge
patterns or the like.
Although a preferred embodiment of a vessel inspection or survey
system, together with an improved method of carrying out an
inspection or survey of the interior of a vessel has been described
hereinabove, those skilled in the art will recognize that various
substitutions and modifications may be made to the system and
method described without departing from the scope and spirit of the
invention as recited in the appended claims.
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